The developing relationship between Stylosanthes and anthracnose after 14 years in a North Queensland pasture. 3. Diversity in the plant population

Abstract

Host-plant diversity in a mixed accession Stylosanthes spp. pasture 14 years after establishment was demonstrated in families derived from seed and in cuttings obtained from the pasture. Glasshouse examination of the progeny from 181 field plants inoculated with 4 different pathogenicity strains of Colletotrichunz gloeosporioides indicated the widest possible spread of diversity in disease reaction. The progeny exhibited wider variation in resistance to the disease than the originally sown accessions, and when transplanted to a field site, plant phenotypic variability became increasingly evident as the progenies matured. Of 1339 transplanted progeny, 369 were not able to be conclusively categorised according to the descriptions of the originally sown accessions, indicating that outcrossing had occurred. The demonstrated plant variability is, arguably, encouraging for the management of anthracnose using genotype mixtures in the vast areas of low-input beef pastures in northern Australia.